It has been known for many years that fuel tanks may become deformed. This is particularly true when tanks are made of plastic. For example, the depth of the tank may vary significantly as a function of various parameters such as temperature, the weight of fuel in the tank, etc.
If precautions are not taken, tank deformations can give rise to erroneous fuel measurements, particularly when measuring a small quantity of fuel remaining in the bottom of a tank.
Errors can have severe consequences when the information from the electrical transducer is used to generate a warning signal informing the driver that the level in the tank has reached a minimum or "reserve" level. The effect of the above-mentioned error can lead to the warning being generated late. In other words, the device may indicate a quantity of fuel that is greater than the quantity actually in the tank.
Attempts have already been made to solve the above problem by means of devices that take their reference from the bottom of the tank.
Such devices are described, for example, in the following documents: US-A-4 184 370, DE-A-3 310 704, US-A-3 935 747, and US-A-3 449 955.
All of those known "bottom-reference" devices include means for urging the level-measuring assembly against the bottom of the tank, i.e. the assembly comprising the support for the float-carrying lever and the support for the electrical transducer.
Those known solutions lead to structures that are complex.
The object of the present invention is to improve existing systems.